The following is a description of three types of vacuum cleaners which differ in design and operation. All of them have as common features a motor-driven fan, a dust collection chamber, and one or more floor treatment devices which are each adapted for a particular purpose.
The canister vacuum cleaner has a housing which can be moved on the floor to be cleaned on wheels and/or runners. The housing contains the motor-fan unit and the dust collection container. The floor treatment device, here referred to as floor nozzle, is connected to the dust collection chamber via a suction hose, and possibly a suction wand connected therebetween. During vacuuming, the housing is moved to the desired position by pulling on the suction wand.
In a stick vacuum cleaner, the motor-fan unit and the dust collection container are also disposed in a housing. A suction wand extends from one end of the housing, connecting the floor nozzle to the dust collection container, and a handle used to maneuver the housing to the desired position extends from the other end.
Uprights do not have as strictly divided a configuration as the two aforementioned types. One feature of an upright is a movable base unit which carries an upper body containing a large dust collection container. The two parts are tiltable relative to each other and can usually be locked in a parked position in which the upper body is nearly upright when the base unit is located on a horizontal floor in a position of use. In this position, the upright stands unsupported. During vacuuming, the above-described locked engagement is released, and the upper body is tilted through a certain angle to an operating position. The tilt angle depends on the height of the user and on the particular purpose of use. A handle is provided on the upper body for maneuvering the entire appliance. The motor-fan unit may be mounted at different locations. WO 2007/008770 A2 describes, for example, securing the fan directly to the upper body. This reduces the ease-of-use because this heavy component produces a torque about the tilt point, which the user must counteract throughout the vacuuming operation. The upright described in WO 2007/008770 A2 has the further drawback is that it is difficult to move from a straight path of travel into a curved path of travel. WO 2004/014209 A1 and EP 0 708 613 A1 describe the fan being configured as a separate unit. Providing a point of rotation between the upper body and the upper region of the fan (EP 0 708 613 A1), or mounting the fan in a rotatable, spherical housing (WO 2004/014209 A1) enables the upright to move along curved paths, thereby improving maneuverability. Also known are uprights in which the motor-fan unit is located in the base unit. In such upright cleaners, the articulated connection between the base unit and the upper body is provided by a hinge-like structure. The air passageway is provided by flexible hoses extending from the base unit to the upper body.
In order to give the user additional options for vacuuming besides vacuum cleaning with the base unit, such as above-the-floor-vacuuming, the air passageway can have an interface and, downstream thereof, a section which is formed by a hose or hose/wand assembly. In most designs, a wand member is held in an insertion receptacle. After removing the wand member from the insertion receptacle, different types of vacuum attachments may be attached to the suction end thereof. The assembly so formed can be used in the same manner as with a conventional canister vacuum cleaner. This is usually done when the upright is in the parked position. It is desired for the vacuum cleaner to remain in this position and not to tip over even when a slight pull is exerted on the hose. WO 2004/014209 A1 describes two alternatives for increasing the stability of an upright in the parked position. In a first variant (FIGS. 1 and 2), the rear wheels are mounted to the upper body and are moved rearward when the upper body is pivoted to an upright position. Such an arrangement of the rear wheels is possible only for small base units that do not have a suction fan. In a second variant (FIG. 6), there is provided an additional stand assembly to increase the footprint in the parked position. This increases the complexity of the design.
Furthermore, vertical stability can be increased by providing the upright with a base unit having a constant, very large footprint. This reduces the ease of maneuverability.